drivers/xen/xencomm.c

   1 /*
   2  * This program is free software; you can redistribute it and/or modify
   3  * it under the terms of the GNU General Public License as published by
   4  * the Free Software Foundation; either version 2 of the License, or
   5  * (at your option) any later version.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  15  *
  16  * Copyright (C) IBM Corp. 2006
  17  *
  18  * Authors: Hollis Blanchard <hollisb@us.ibm.com>
  19  */
  20
  21 #include <linux/gfp.h>
  22 #include <linux/mm.h>
  23 #include <asm/page.h>
  24 #include <xen/xencomm.h>
  25 #include <xen/interface/xen.h>
  26 #ifdef __ia64__
  27 #include <asm/xen/xencomm.h>    /* for is_kern_addr() */
  28 #endif
  29
  30 #ifdef HAVE_XEN_PLATFORM_COMPAT_H
  31 #include <xen/platform-compat.h>
  32 #endif
  33
  34 static int xencomm_init(struct xencomm_desc *desc,
  35                         void *buffer, unsigned long bytes)
  36 {
  37         unsigned long recorded = 0;
  38         int i = 0;
  39
  40         while ((recorded < bytes) && (i < desc->nr_addrs)) {
  41                 unsigned long vaddr = (unsigned long)buffer + recorded;
  42                 unsigned long paddr;
  43                 int offset;
  44                 int chunksz;
  45
  46                 offset = vaddr % PAGE_SIZE; /* handle partial pages */
  47                 chunksz = min(PAGE_SIZE - offset, bytes - recorded);
  48
  49                 paddr = xencomm_vtop(vaddr);
  50                 if (paddr == ~0UL) {
  51                         printk(KERN_DEBUG "%s: couldn't translate vaddr %lx\n",
  52                                __func__, vaddr);
  53                         return -EINVAL;
  54                 }
  55
  56                 desc->address[i++] = paddr;
  57                 recorded += chunksz;
  58         }
  59
  60         if (recorded < bytes) {
  61                 printk(KERN_DEBUG
  62                        "%s: could only translate %ld of %ld bytes\n",
  63                        __func__, recorded, bytes);
  64                 return -ENOSPC;
  65         }
  66
  67         /* mark remaining addresses invalid (just for safety) */
  68         while (i < desc->nr_addrs)
  69                 desc->address[i++] = XENCOMM_INVALID;
  70
  71         desc->magic = XENCOMM_MAGIC;
  72
  73         return 0;
  74 }
  75
  76 static struct xencomm_desc *xencomm_alloc(gfp_t gfp_mask,
  77                                           void *buffer, unsigned long bytes)
  78 {
  79         struct xencomm_desc *desc;
  80         unsigned long buffer_ulong = (unsigned long)buffer;
  81         unsigned long start = buffer_ulong & PAGE_MASK;
  82         unsigned long end = (buffer_ulong + bytes) | ~PAGE_MASK;
  83         unsigned long nr_addrs = (end - start + 1) >> PAGE_SHIFT;
  84         unsigned long size = sizeof(*desc) +
  85                 sizeof(desc->address[0]) * nr_addrs;
  86
  87         /*
  88          * slab allocator returns at least sizeof(void*) aligned pointer.
  89          * When sizeof(*desc) > sizeof(void*), struct xencomm_desc might
  90          * cross page boundary.
  91          */
  92         if (sizeof(*desc) > sizeof(void *)) {
  93                 unsigned long order = get_order(size);
  94                 desc = (struct xencomm_desc *)__get_free_pages(gfp_mask,
  95                                                                order);
  96                 if (desc == NULL)
  97                         return NULL;
  98
  99                 desc->nr_addrs =
 100                         ((PAGE_SIZE << order) - sizeof(struct xencomm_desc)) /
 101                         sizeof(*desc->address);
 102         } else {
 103                 desc = kmalloc(size, gfp_mask);
 104                 if (desc == NULL)
 105                         return NULL;
 106
 107                 desc->nr_addrs = nr_addrs;
 108         }
 109         return desc;
 110 }
 111
 112 void xencomm_free(struct xencomm_handle *desc)
 113 {
 114         if (desc && !((ulong)desc & XENCOMM_INLINE_FLAG)) {
 115                 struct xencomm_desc *desc__ = (struct xencomm_desc *)desc;
 116                 if (sizeof(*desc__) > sizeof(void *)) {
 117                         unsigned long size = sizeof(*desc__) +
 118                                 sizeof(desc__->address[0]) * desc__->nr_addrs;
 119                         unsigned long order = get_order(size);
 120                         free_pages((unsigned long)__va(desc), order);
 121                 } else
 122                         kfree(__va(desc));
 123         }
 124 }
 125
 126 static int xencomm_create(void *buffer, unsigned long bytes,
 127                           struct xencomm_desc **ret, gfp_t gfp_mask)
 128 {
 129         struct xencomm_desc *desc;
 130         int rc;
 131
 132         pr_debug("%s: %p[%ld]\n", __func__, buffer, bytes);
 133
 134         if (bytes == 0) {
 135                 /* don't create a descriptor; Xen recognizes NULL. */
 136                 BUG_ON(buffer != NULL);
 137                 *ret = NULL;
 138                 return 0;
 139         }
 140
 141         BUG_ON(buffer == NULL); /* 'bytes' is non-zero */
 142
 143         desc = xencomm_alloc(gfp_mask, buffer, bytes);
 144         if (!desc) {
 145                 printk(KERN_DEBUG "%s failure\n", "xencomm_alloc");
 146                 return -ENOMEM;
 147         }
 148
 149         rc = xencomm_init(desc, buffer, bytes);
 150         if (rc) {
 151                 printk(KERN_DEBUG "%s failure: %d\n", "xencomm_init", rc);
 152                 xencomm_free((struct xencomm_handle *)__pa(desc));
 153                 return rc;
 154         }
 155
 156         *ret = desc;
 157         return 0;
 158 }
 159
 160 /* check if memory address is within VMALLOC region  */
 161 static int is_phys_contiguous(unsigned long addr)
 162 {
 163         if (!is_kernel_addr(addr))
 164                 return 0;
 165
 166         return (addr < VMALLOC_START) || (addr >= VMALLOC_END);
 167 }
 168
 169 static struct xencomm_handle *xencomm_create_inline(void *ptr)
 170 {
 171         unsigned long paddr;
 172
 173         BUG_ON(!is_phys_contiguous((unsigned long)ptr));
 174
 175         paddr = (unsigned long)xencomm_pa(ptr);
 176         BUG_ON(paddr & XENCOMM_INLINE_FLAG);
 177         return (struct xencomm_handle *)(paddr | XENCOMM_INLINE_FLAG);
 178 }
 179
 180 /* "mini" routine, for stack-based communications: */
 181 static int xencomm_create_mini(void *buffer,
 182         unsigned long bytes, struct xencomm_mini *xc_desc,
 183         struct xencomm_desc **ret)
 184 {
 185         int rc = 0;
 186         struct xencomm_desc *desc;
 187         BUG_ON(((unsigned long)xc_desc) % sizeof(*xc_desc) != 0);
 188
 189         desc = (void *)xc_desc;
 190
 191         desc->nr_addrs = XENCOMM_MINI_ADDRS;
 192
 193         rc = xencomm_init(desc, buffer, bytes);
 194         if (!rc)
 195                 *ret = desc;
 196
 197         return rc;
 198 }
 199
 200 struct xencomm_handle *xencomm_map(void *ptr, unsigned long bytes)
 201 {
 202         int rc;
 203         struct xencomm_desc *desc;
 204
 205         if (is_phys_contiguous((unsigned long)ptr))
 206                 return xencomm_create_inline(ptr);
 207
 208         rc = xencomm_create(ptr, bytes, &desc, GFP_KERNEL);
 209
 210         if (rc || desc == NULL)
 211                 return NULL;
 212
 213         return xencomm_pa(desc);
 214 }
 215
 216 struct xencomm_handle *__xencomm_map_no_alloc(void *ptr, unsigned long bytes,
 217                         struct xencomm_mini *xc_desc)
 218 {
 219         int rc;
 220         struct xencomm_desc *desc = NULL;
 221
 222         if (is_phys_contiguous((unsigned long)ptr))
 223                 return xencomm_create_inline(ptr);
 224
 225         rc = xencomm_create_mini(ptr, bytes, xc_desc,
 226                                 &desc);
 227
 228         if (rc)
 229                 return NULL;
 230
 231         return xencomm_pa(desc);
 232 }